BC Weather Extremes: Morning vs. Afternoon

shuswaplake

View of Shuswap Lake from the Larch Hills Traverse

As we head into another heatwave, it becomes an interesting time to revisit the temperature extremes around the province.

CBC radio typically mentions the “current” province hotspot and coldspot during the afternoon weather forecasts.

The morning radio shows covering the same listening area will sometimes mention the weather extremes, and if you’re an astute listener you will notice that temperature extremes in the morning are often radically different than the afternoon. These differences are analyzed below.

Three separate CBC radio shows cover the province in the morning and five in the afternoon, but for simplicity sake, we will just look at the entire province as one area.

There are some other factors to consider, such as whether or not to include the lighthouse stations where no one lives permanently and/or stations that don’t report hourly. Also, some stations in the north only report hourly a few times per day, and haven’t recorded the daily highs and lows for several years now, so they have to be dropped from the list (namely Tetsa River and Muncho Lake).

To make up for the lack of coverage in the north I’ve added Atlin to the list which does not report hourly data. The lighthouse stations have also been included. The 123 usable weather stations were divided into 8 regions shown below.

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While the temperatures are much warmer in the south than the north, there were some surprising findings on where the hottest locations can be found. Fort Nelson averages 3 days per year as the hottest place in BC in the afternoon (I supposed this should not be too much of a surprise given the fact that the Canadian hotspot yesterday was in the Northwest Territories). By comparison, Vancouver averages 0.5 days per year at the airport and 1.75 days downtown. Even in the hot southern interior, Penticton is not that much higher than Fort Nelson with 3.75 days per year.

Temperature extremes can be found at almost every weather station in the province. Only two weather stations (Powell River and Whistler) never recorded an extreme of any kind in the between 2015 and 2018.

Six stations recorded at least one extreme in each of the four categories (highest daily maximum, lowest daily maximum, highest daily minimum, and lowest daily minimum). Chetwynd, Cranbrook, Dawson Creek, both Fort Nelson stations, and Golden all recorded at least one day in each category. That’s 40% of the stations in the northern interior plus two in the southeast.

Keep in mind that this is just four years of data. I have not looked at other years, but I happened to notice recently that Tatlayoko Lake in the Chilcotin was the hottest place, not just in BC, but all of Canada (it did not achieve this feat in the previous four years), so clearly a longer time frame would increase the number of locations setting daily Provincial temperature extremes.

HIGH HIGHS

It is quite rare for the central interior to record the hottest afternoon temperature in the province. Smithers and Quesnel take most of those with one day each per year. Interestingly enough, it’s more common to find the hottest place in the province 1000 km north in Fort Nelson.

hottestbc1

 

40% of hot days throughout the year are recorded in the southwestern interior, including the vast majority of summer days. The southwest interior covers the Okangan-Shuswap to the Coast-Cascade Mountains. That includes 4 of the top 5 in the graph below (Warfield is in southeastern BC).

hottestbc2

HIGH LOWS

How does this compare to the hot spots in the morning hours, you ask? Well, here are the same two graphs as above.

MAXMIN

MAXMIN2

Because of rounding error, the Northern Interior shows 0% of days as the warmest place in the mornings, but it’s actually 1.5 days per year (0.75 days in Fort Nelson, 0.5 days in Chetwynd, and 0.25 days in Dawson Creek). The Only area where you never find the morning hotspot is the Central Interior (Cariboo, Chilcotin, Prince George, Bulkley, Nechako area).

Notice that the lighthouse stations jump up to almost 70% of days. This is because the winds off the ocean combined with higher humidity keep overnight temperature high. Many of these stations budge by a mere 4 degrees between morning and afternoon. By contrast, the central interior stations average up to 16 degrees of average daily temperature swings. The three highest swings in the province are all in the Central Interior (Puntzi Mountain, Tatlayoko Lake, and Burns Lake).

Much of the rest of the interior has high diurnal temperature variations as well, and thus are more likely to be the hot spot in the afternoon than the morning. For example, Ashcroft averages more than 38 days per year as the afternoon hot spot, but only 7 in the morning.

LOW LOWS

The morning cold spots are almost all in the interior. Fort Nelson leads the way with just under 70 per year following Burns Lake in the central interior, and Yoho National Park (the highest elevation weather station in BC) in the southeastern interior.

4 of the top 7 morning cold spots are in the central interior because of the high diurnal temperature variations (temperature change throughout the day).

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43% of the time the coldest place in BC can be found in the central interior versus 42% of the time in the northern interior. This changes significantly in the afternoon were only 5% of days are coldest in the central interior.

Vancouver Island and the North  & Central Coast were never the coldest places in BC in the afternoon over these four years.  Princeton put the southwestern interior on the board with two readings in four years while two Whistler area stations each recorded one occurrence as the coldest spot in the province in the morning (putting the South Coast on the board).

min2

LOW HIGHS

The central interior warms up so dramatically most days that Burns Lake, Puntzi Mountain, Clinton, and Tatlayoko Lake combined only manage 6 days per year (once every two months) as the coldest place in the province in the afternoon. By contrast, one of these stations is the coldest place in BC 154 days per year. That’s once ever 2.4 days!

The odds of Revelstoke in the south of being the coldest place in BC come the afternoon is the same as Burns Lake and higher than Tatlayoko Lake!

minmax1

minmax2

COMBINED

So, combining all categories, how many times per year would the CBC be mentioning each location? Here is a list of selected places:

  • 1) Fort Nelson = 146 (Northern Interior)
  • 2) Yoho National Park = 89 (Southeastern Interior)
  • 3) Osoyoos = 63 (Southwestern Interior)
  • 4) Dease Lake = 61
  • 5) Burns Lake = 58 (Central Interior)
  • 6) Lytton = 56
  • 7) Kindakun Rocks = 54 (Lighthouse)
  • 8) Ashcroft = 45
  • 31) White Rock = 18 (South Coast)
  • 36) Kamloops = 12
  • 41) Malahat = 9.75 (Vancouver Island)
  • 49) Bella Coola = 7.75 (North & Central Coast)
  • 59) Penticton = 4.75
  • 62) Kelowna (UBCO) = 4.5
  • 74) Cranbrook = 3
  • 74) Prince George =3
  • 76) Victoria (Airport) = 2.75
  • 87) Williams Lake = 2.25
  • 90) Merritt = 2
  • 91) Nanaimo = 1.75
  • 113) Kelowna (Airport) = 0.25

INTERESTING STATIONS OF NOTE

Yoho National Park (Southeastern Interior): The highest elevation station in BC that has a lot of cold afternoon temperature extremes.

Fort Nelson: Has the coldest winters in BC, recording the morning and afternoon extreme cold temperatures more than anyone else. By contrast, it never records the coldest extreme during the summer months.

Osoyoos: This south Okanagan community has the highest average daily maximum temperature for the year. Some of the other stations in the southwestern interior, namely Lytton and Ashcroft, have more extremely hot days (days above 35°C), but Osoyoos has a warmer average high throughout the year.

Osoyoos also has a lot of warm nights with the most number of “warmest mornings” throughout the year among non-lighthouse stations.

DIFFERENCES BETWEEN MORNING AND AFTERNOON

If you had a radio station (CBC or private) listing the morning and afternoon extremes, there would be some serious differences.

Over the past four years (2015-2018), the morning radio station would mention Burns Lake 230 times (as the coldest spot) while the afternoon station would only mention Burns Lake twice.

By contrast, the windswept lighthouse stations that account for 20% of the provincial weather stations recorded just a single minimum temperature in the morning (Rose Spit on Haida Gwaii on June 19, 2015) versus a four year total of 372 occurrences as the minimum maximum temperature.

 

 

 

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Sunshine Hours in British Columbia

Taking every single weather station in the province that has recorded bright hours of sunshine — and adjusting for differences between periods of record — gives the summary at the bottom. Sunshine hours started in the mid-1950s and ended around 2001. A few stations kept recording for another decade or so, but there are no weather stations in BC or Canada today recording sunshine hours.

Note that there is margin of error not shown here so the order is only a best estimate, especially for some of the stations that were in existence for as little as five years.  Even for those that have been around for several decades, there is enough margin of error to not know if (for example) Cranbrook or Victoria (Gonzales Hill) is the sunniest place in the province. It is safe to say that those two weather stations are the top two, but the order is debatable.

In BC, some of the major factors reducing the sunshine hours are valley cloud, fog, and mountains. This is why you find some stations with extremely low sunshine hours in the winter months.

sunshineBC.png

 

 

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How Cold Can it Get in Lumby?

We made it through most of January before winter hit this year, but February made up for lost time with the most dramatic late season turnaround on record.

The entire month remained cold with no warmup until the second week of March, but the extreme lows were less impressive with the official low at the Vernon weather station being -22.7°C. Unofficial backyard readings in the Lumby area reported below -25° in spots.

During the cold snap in February and early March, several people asked me about how cold Lumby can get.

The answer is a bit long, so let’s start off summarizing the weather stations we have available from Environment Canada.

LumbyWS2

Since the late 1800s there have been 17 weather stations recording temperature in the Lumby-Cherryville-Vernon area. Most have been relatively short lived, but the Coldstream Ranch location (the current official reading for Vernon) enjoys continuous records from 1900 to the present.

Lumbyws.png

The official data confirms what locals already know — Lumby can get very cold at night.

This is achieved by very strong temperature inversions that develop under calm conditions and clear nighttime skies. The lack of wind allows cold air to sink and pool in the low, flat valley bottom around Lumby. These conditions put the Village of Lumby almost on  par with Nicklen Lake (on the Aberdeen plateau some 800m higher) as the coldest spot in the area. The highest elevation weather station location at Silver Star does not get these extremely cold nights on account of the geography allowing cold air to slide on down hill past the ski resort, but still ranks as the third coldest weather station on the list.

LUMBYWEATHER

My place on a hillside in Lumby typical has overnight winter temperatures similar to the Vernon weather station in Coldstream, but if I take a drive downtown the temperature drops several degrees. Even more pronounced is a drive out to Whitevale.

As the next graph shows, Lumby is often five degrees colder than Vernon. In fact, the average yearly extreme low temperature in Lumby was six degrees Celsius colder than Vernon (Coldstream Ranch) between 1996 and 2010. During very cold winters this difference tends to be even greater. (I suspect that the Lumby data from the 1960s was a different location given the warmer temperatures relative to Vernon.)

Lumbyws4

Looking back over the past 123 years, 48% of the “winter” extreme lows took place in January, 22% in December, 17% in February, 6.5% in November, 5.7% in March, and 0.8% in October. Yes, the coldest temperature once occurred in October!

LumbyWS5

The number of weather stations in Canada has been in decline since the 1980s, but the decline in the Lumby area didn’t start until mid-1990s. Still, the number of stations have been droping over the past 20 years, going from a high of eight stations to two today. This makes new extreme weather records less likely today than in the past because of less coverage.

It also makes the tracking of climate change almost impossible, especially in terms of precipitation. In our area, only Silver Star and Vernon (Coldstream Ranch) remain. The Silver Star station is intermittent during the summer months and Vernon station is automated, and automated stations are unreliable at recording precipitation. Snowfall is not recorded at all with the automated station.

lumbyws3

Since the weather records near Lumby are fairly spotty, we much extrapolate from nearby stations in Vernon and elsewhere to estimate Lumby’s extreme cold.

Estimates for the extreme temperatures in Lumby can best be derived by analyzing the 119 years of Vernon-Coldstream Ranch data. It’s not an exact science, however, because there are some rare days when the temperature is colder in Vernon than Lumby (for example) so a single station should not be used for this exercise.

Looking at all data within 200 km of Lumby (and indeed, the entire province) reveals that there were two cold spells head and shoulders above the rest. The most recent was the winter of the 1968/69 (the coldest winter in BC history) and the one before that was January of 1950 (the coldest month on record in BC).

The Coldstream Ranch data doesn’t give 1950 justice because the extreme cold seems to have missed that station relative to almost all other stations (still, -35.6°C makes the top 3).

A snapshot of January 1950 shows that this month was the first and last time:

  • Fauquier dropped to -30°C (the -31.7°C reading was 1.5° colder than the second coldest extreme set in December 1968)
  • Armstrong hit -40°C (the -42.2°C low was 2.8° coldest than the next coldest record from January 1943)
  • Westwold hit -45°C (bottoming out at -45.6 — four degrees below than the next coldest day from January 1969)

The winter of 1968/69 was impressively cold from late December to early February, with Vernon dropping to -39°C. A little further south at the Kelowna airport, the temperature dipped to -36°C (no station existed at the airport in 1950).

So how cold was Lumby those years?

If the low lying areas of Lumby tend to be 6 degrees colder than Vernon +/- 4 degrees, we can conservatively estimate a temperature of -45°C in at least one of those years. That would be pushing -50°F. Not bad, eh?

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Maliciousness or Incompetence?

“Never attribute to malice that which is adequately explained by stupidity.”
~ Hanlon’s razor

When we repeatedly accuse the media of lying, we are often mistaking sloppy fact checking for malice. Otherwise, why would there be so many mistakes in apolitical articles such as ones about the weather? That is not to say there aren’t gross examples of lying (there are), but it’s not as common as political hacks of all stripes make it out to be.

Journalists are generalists, not specialists, so they tend to have knowledge on a much more broad array of topics than the general public, but their grasp of each individual topic is quite shallow. They have just enough knowledge to dangerous, but not enough to be useful.

In line with Hanlon’s razor, this article is one example.

The first error is the misleading title. No one says, “the runner broke a record” when he wasn’t even close to beating the all time record, so why say it about the weather?

To set up the second error, we must understand that there are two existing weather stations in Kelowna — one at the airport (opened in 1968) and one at UBCO (opened in 2012). Since the 1800s Kelowna has seen 20 weather stations in the area come and go with the airport being unique among them all for having much colder nights. The airport sits in a frost hollow where cold air pools at night. This means that the airport station has an average temperature that’s at least a degree colder than the rest of the city — even compared to stations less than 1 km away.

KELOWNA3.png

So when the article states that February 2019 was “-6.5 C colder than normal”, it is wrong. Wrong because it compares the new University of British Columbia Okanagan (UBCO) station to the airport normal. In actual fact, the Kelowna airport was 7.6°C colder than normal in 2019.

Also, it’s wrong to say the temperature is “6.5 C colder than normal” because that’s a double negative, but I won’t get hung up on this fact because we all know what they mean.

Moving on, the news article states that this was the coldest February since 1975, but here again they are comparing the UBCO station with the data from the airport. If they want to properly compare apples to apples, they need to use the airport data from 2019 and compare that to the airport data from 1975.

As the article accurately states, the average temperature in 1975 was -7.8°C, but in 2019, the airport averaged -8.5°C (UBCO was -7.4C). Therefore, 2019 was indeed the coldest month on record at the Kelowna airport (with the first February being 1969).

The article goes on to state that the coldest temperature for the month was -20.2°C, which is again the UBCO figure, but the airport bottomed out at -20.9°C.

Other stations have existed in Kelowna and the rest of the Okanagan valley prior to 1968, and this data shows there that 1936 was much colder than any other year including 2019. Even warmer locations were colder in 1936 than the airport was in 2019.

As Castanet rightly states, 2019 was the second coldest February on record in Penticton [with 1936 being the coldest by a wide margin].

PentictonBC

The statement about Williams Lake and Prince George experiencing their coldest February on record can only be considered accurate if all stations in existence in 1936 are ignored. Because 1936 was so much colder than 2019, it isn’t necessary to compare the exact same location to accurately conclude that 1936 was much colder.

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Shattered Record in Saskatoon?

It’s really interesting to see articles like this exclaiming that Saskatoon SHATTERED a 112 year old record as if this is something that only happens every hundred years or so.

You can see the data in the graph below and decide for yourself whether or not the record was shattered.

sask

The blue line represents the daily record low and the orange line represents the 2019 daily lows.

In actual fact, it is really not that hard to set new records even when you have data that stretches back 112 years.

As of yesterday, we are 38 days into the year, and thus, with 112 years worth of data the odds of setting a record low or high so far is just under 50 percent with the probability of setting just a record low at 29%. The odds of it snowing yesterday or the odds of Donald Trump getting elected president were lower than that.

It is being quite cold, that is for sure, but setting record colds is not really as unusual or unbelievable as the media portrays it to be.

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Is Extreme Cold Caused by Climate Change?

Several articles like this one are making the rounds, claiming that the extreme cold is caused by climate change.

Only a momentary glance at the data shows that this is complete hogwash. The fact that a plethora of supposedly smart scientists shared it makes it no less laughable.

chinesehoax

Climate change causes many things like more floods and heatwaves, I’ve sure, but for this “fact check”, I’m only investigating the claim about it causing extreme cold.

The data does not bare it out anywhere on earth that I can find. It seems to me that there’s a segment of the population that wants to believe that climate change causes EVERYTHING to get worse so badly that they aren’t satisfied with some or most of the things getting worse, so they just make up fairy tales to make it out to be 100% bad.

Or maybe it’s just a lazy way of refuting those who say “look it’s cold outside, so there must not be any global warming.”

In either case, it makes no logical sense whatsoever to claim extremes are increasing at both ends. If you have more extreme heat and more extreme cold, you are saying that the standard deviations are getting larger over time. There’s no evidence for this either, so the only scientifically accurate statement would be that extremes at one end are going up and extremes at the other are going down.

Winnipeg, Manitoba hit -40 degrees yesterday, and this is supposed to be caused by climate change. Okay, let’s graph the number of -40 days since records began in 1872.

Winnipeg-40

No upward tick there, so let’s try another spot.

lethbridge-40

Nothing here in over 20 years.

Let’s try going really cold, like -45C/-49F in Regina (the places above don’t get that cold).

Regina-45.png

Nothing here since the 1950s.

Since this is a BC based site, let’s try a few of spots in BC showing their most extreme cold days.

Victoria-10

Kamloops-30b.png

kelowna-20

penticton-22

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And here we see the same sort of trend with the extreme cold all but disappearing after the 1960s — yet, climate change is causing more extreme cold? The level of cognitive dissonance is deafening.

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Warmest December Since 1939

elnino

Going into the winter of 2018/2019, we were expected a mild one given the fact that El Niño was strong, but I don’t think anyone predicted it would the warmest December since 1939 in southern British Columbia.

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vancouverdec

pentictondec

A little further north in the central part of the province, it was warm, but certainly not close to the warmest in the past 80 years. Here is what the December climate record looks like for Tatalyoko Lake.

tatlayokolake

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